Techniques for using collision avoidance signaling for co-existence with unlicensed networks

ABSTRACT

Systems and techniques are disclosed to manage coexistence of wireless technologies, including 5G unlicensed transmissions, with 802.11 transmissions in the unlicensed band. Aspects of the present disclosure include collision avoidance to achieve fair access of transmissions on unlicensed bands. Other aspects, embodiments, and features are also claimed and described.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to U.S. patent application Ser. No.______, filed on the same day and titled “Techniques for Using TrafficMonitoring for Co-existence with Unlicensed Networks” (Atty. Docket No.151980/49606.269US01), the entire disclosure of which is incorporatedherein by reference.

TECHNICAL FIELD

This application relates to wireless communication systems, and moreparticularly to access technologies that are deployed in unlicensedbands where the incumbent technology is WiFi. Embodiments can enable andprovide co-existence between licensed and unlicensed communicationnetworks/systems.

INTRODUCTION

Current wireless practices involve the use of a number of accesstechnologies such as 802.11 (WiFi), 802.15.1 (Bluetooth) and 802.15.4(ZigBee) in 2.4 GHz ISM (Industrial, Scientific and Medical) and 5 GHzU-NII (Unlicensed National Information Infrastructure) bands. Thesebands are known as “unlicensed” bands. Data offload in unlicensed bandstoday is primarily carried out using WiFi. Unlicensed bands havetraditionally been unsuitable for use with access technologies designedprimarily to operate in “licensed” frequencies. Also WiFi efficiency canbe impacted by LTE transmissions.

LTE features such as Carrier Aggregation (CA), however, have made itpossible to operate these technologies in unlicensed bands as well,leading to the introduction of LTE-U systems. These systems may offersignificantly better coverage and higher spectral efficiency compared toWiFi, while allowing seamless flow of data across licensed andunlicensed bands. These advantages may allow higher data rates, andseamless use of both licensed and unlicensed bands with high reliabilityand robust mobility through a licensed anchor carrier.

LTE design elements in unlicensed band ensure that LTE-U co-exists withcurrent access technologies such as WiFi on “fair” and “friendly” bases.Challenges exist in detecting and avoiding collisions with ongoing WiFisignal traffic. Although many broadband access systems have interferencemanagement mechanisms, these are generally designed to work forterminals of the same technology rather than in heterogeneous wirelessprotocols and standards that adopt asynchronous time slots.

SUMMARY

The following summarizes some aspects of the present disclosure toprovide a basic understanding of the discussed technology. This summaryis not an extensive overview of all contemplated features of thedisclosure, and is intended neither to identify key or critical elementsof all aspects of the disclosure nor to delineate the scope of any orall aspects of the disclosure. Its sole purpose is to present someconcepts of one or more aspects of the disclosure in summary form as aprelude to the more detailed description that is presented later.

In one aspect of the disclosure, a method for managing wirelesscommunications is provided that includes transmitting, using a firstwireless communication device, one or more collision avoidance signalsto one or more receiving wireless communication devices, the collisionavoidance signals formatted to allow the one or more receiving wirelesscommunication devices to receive the collision avoidance signals usingeither a first radio access technology or a second radio accesstechnology, the collision avoidance signals also including informationto allow the one or more receiving wireless communication devices toavoid transmission collisions with the first wireless communicationdevice during a transmission time slot; and communicating, using thefirst wireless communication device, data with a second wirelesscommunication device during the transmission time slot.

In an additional aspect of the disclosure, a wireless communicationdevice is provided that includes a processor and a co-existence modulethat monitor a channel of an unlicensed band during a subset of timeslots of the channel; and a transmitter configured to: transmit one ormore collision avoidance signals to one or more receiving wirelesscommunication devices, the collision avoidance signals formatted toallow the one or more receiving wireless communication devices toreceive the collision avoidance signals using either a first radioaccess technology or a second radio access technology, the collisionavoidance signals also including information to the allow the receivingwireless communication devices to avoid transmission collisions with thefirst wireless communication device during a transmission time slot; andcommunicate data with a second wireless communication device during thetransmission time slot.

In another aspect of the disclosure, a wireless communication device isprovided that includes means for transmitting one or more collisionavoidance signals to one or more receiving wireless communicationdevices, the collision avoidance signals formatted to allow the one ormore receiving wireless communication devices to receive the collisionavoidance signals using either a first radio access technology or asecond radio access technology, the collision avoidance signals alsoincluding information to the allow the one or more receiving wirelesscommunication devices to avoid transmission collisions with the firstwireless communication device during a transmission time slot; and meansfor communicating data with a second wireless communication deviceduring the transmission time slot.

Other aspects, features, and embodiments of the present invention willbecome apparent to those of ordinary skill in the art, upon reviewingthe following description of specific, exemplary embodiments of thepresent invention in conjunction with the accompanying figures. Whilefeatures of the present invention may be discussed relative to certainembodiments and figures below, all embodiments of the present inventioncan include one or more of the advantageous features discussed herein.In other words, while one or more embodiments may be discussed as havingcertain advantageous features, one or more of such features may also beused in accordance with the various embodiments of the inventiondiscussed herein. In similar fashion, while exemplary embodiments may bediscussed below as device, system, or method embodiments it should beunderstood that such exemplary embodiments can be implemented in variousdevices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication network in accordance withvarious aspects of the present disclosure.

FIG. 2 illustrates a wireless communication network with overlapping802.11 and cellular networks in accordance with various aspects of thepresent disclosure.

FIG. 3 illustrates a wireless communication network device in accordancewith various aspects of the present disclosure.

FIG. 4 is a flowchart illustrating a method of monitoring for 802.11signal traffic in accordance with various aspects of the presentdisclosure.

FIG. 5 is a flowchart illustrating a method of passive 802.11 signaltraffic monitoring in accordance with various aspects of the presentdisclosure.

FIG. 6 is a flowchart illustrating a method of active 802.11 signaltraffic monitoring in accordance with various aspects of the presentdisclosure.

FIG. 7 is a flowchart illustrating a method of implementing a dynamicduty cycle by dividing a channel into time slots and monitoring for802.11 signal traffic in a subset of those time slots in accordance withvarious aspects of the present disclosure.

FIG. 8 is a flowchart illustrating a method of implementing a dynamicduty cycle by dividing a channel into time slots, dividing the timeslots into sub-slots, and monitoring for 802.11 signal traffic in thesub-slots of a subset of those time slots in accordance with variousaspects of the present disclosure.

FIG. 9 illustrates a number of transmissions during a dynamic duty cycleon an unlicensed network in accordance with FIGS. 7-8.

FIG. 10 illustrates an exemplary set of time slot divisions during atime period on an unlicensed band channel, in accordance with FIG. 7.

FIG. 11 illustrates an exemplary set of time slots on an unlicensed bandchannel in conjunction with the discussion of sub-slots in FIG. 8.

FIG. 12 illustrates an aspect of an exemplary 802.11 transmissionincluding preambles in accordance with various aspects of the presentdisclosure.

FIG. 13 illustrates another aspect of an exemplary 802.11 transmissionincluding a PPDU surrounded by OFDM symbols in accordance with variousaspects of the present disclosure.

FIG. 14 illustrates a diagram of transmitting and receiving collisionavoidance signals for 802.11 compatible devices in accordance withvarious aspects of the present disclosure.

FIG. 15 illustrates a diagram of an alternative for transmittingcollision avoidance signals for 802.11 compatible devices in accordancewith various aspects of the present disclosure.

FIG. 16 illustrates a diagram of another alternative for transmittingand receiving collision avoidance signals for 802.11 compatible devicesin accordance with various aspects of the present disclosure.

FIG. 17 is a flowchart illustrating a method for implementing collisionavoidance signaling in accordance with FIGS. 14-16.

FIG. 18 illustrates a diagram of another alternative for transmittingcollision avoidance signals for 802.11 compatible devices in accordancewith various aspects of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with theappended drawings, is intended as a description of variousconfigurations and is not intended to represent the only configurationsin which the concepts described herein may be practiced. The detaileddescription includes specific details for the purpose of providing athorough understanding of the various concepts. However, it will beapparent to those skilled in the art that these concepts may bepracticed without these specific details. In some instances, well-knownstructures and components are shown in block diagram form in order toavoid obscuring such concepts.

The techniques described herein may be used for various wirelesscommunication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA andother networks. The terms “network” and “system” are often usedinterchangeably. A CDMA network may implement a radio technology such asUniversal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includesWideband CDMA (WCDMA) and other variants of CDMA, while cdma2000 coversIS-2000, IS-95 and IS-856 standards. A TDMA network may implement aradio technology such as Global System for Mobile Communications (GSM).An OFDMA network may implement a radio technology such as Evolved UTRA(E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16(WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part ofUniversal Mobile Telecommunication System (UMTS). 3GPP Long TermEvolution (LTE) and LTE-Advanced (LTE-A) are new releases of UMTS thatuse E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described indocuments from an organization named “3rd Generation PartnershipProject” (3GPP). CDMA2000 and UMB are described in documents from anorganization named “3rd Generation Partnership Project 2” (3GPP2). Thetechniques described herein may be used for the wireless networks andradio technologies mentioned above as well as other wireless networksand radio technologies, such as a next generation (e.g., 5th Generation(5G)) network.

Many aspects are described in terms of sequences of actions to beperformed by, for example, elements of a computing device. It will berecognized that various actions described herein can be performed byspecific circuits (e.g., Application Specific Integrated Circuits(ASICs)), by program instructions being executed by one or moreprocessors, or by a combination of both. In addition, for each of theaspects described herein, the corresponding form of any such aspect maybe implemented as, for example, “logic configured to” perform thedescribed action.

Embodiments of the present disclosure introduce systems and techniquesto manage coexistence of wireless technologies with WiFi. In particular,aspects of the present disclosure include (1) channel selection, (2)802.11 traffic monitoring and coordinated access, and (3) collisionavoidance to achieve fair access of transmissions on unlicensed bands.The use of wireless technologies such as 5G in unlicensed bands mayoffer significantly better coverage and higher spectral efficiency than802.11 networks alone, while providing seamless flow of data acrosslicensed and unlicensed bands in a single core network.

FIG. 1 is a diagram of an exemplary wireless communications environment100 according to embodiments of the present disclosure. Thecommunications environment 100 may include one or more base stations 103that can support communication for a number of user equipments (UEs)101, 102 as well as a core network 111. A UE 101, 102 may communicatewith a base station 103 via downlink and uplink. The downlink (orforward link) refers to the communication link from the base station 103to the UE 101, 102, and the uplink (or reverse link) refers to thecommunication link from the UE 101, 102 to the base station 103.

A base station 103 may transmit data and control information on thedownlink to a UE 101, 102 and/or may receive data and controlinformation on the uplink from the UE 101, 102. In some embodiments, theUEs 101, 102 may be any wireless communication device allowing a user tocommunicate over a communications network (e.g., a mobile/cellularphone, a smartphone, a personal digital assistant, a wireless modem, arouter, personal computer, laptop computer, a tablet computer, server,entertainment device, an appliance, Internet of Things (IOT)/Internet ofEverything (IOE) capable device, in-vehicle communication device (e.g.,an automobile), etc.), and may be alternatively referred to in differentradio access technology (RAT) environments as a User Device (UD), aMobile Station (MS), a Subscriber Station (STA), a User Equipment (UE),a Subscriber Unit, a terminal, etc.

UEs 101, 102 may be dispersed throughout the communications environment100, as shown, and each UE 101, 102 may be stationary or mobile. Thewireless communication network 100 is one example of a network to whichvarious aspects of the disclosure apply.

Each base station 103 may provide communication coverage for aparticular geographic area. In 3GPP, the term “cell” can refer to thisparticular geographic coverage area of a base station and/or a basestation subsystem serving the coverage area, depending on the context inwhich the term is used. In this regard, a base station 103 may providecommunication coverage for a macro cell or a small cell (e.g., a picocell, a femto cell, etc.), and/or other types of cell. A macro cellgenerally covers a relatively large geographic area (e.g., severalkilometers in radius) and may allow unrestricted access by UEs withservice subscriptions with the network provider. A pico cell wouldgenerally cover a relatively smaller geographic area and may allowunrestricted access by UEs with service subscriptions with the networkprovider. A femto cell would also generally cover a relatively smallgeographic area (e.g., a home) and, in addition to unrestricted access,may also provide restricted access by UEs having an association with thefemto cell (e.g., UEs in a closed subscriber group (CSG), UEs for usersin the home, and the like). A base station for a macro cell may bereferred to as a macro base station. A base station for a pico cell maybe referred to as a pico base station. And, a base station for a femtocell may be referred to as a femto base station or a home base station.A base station 104 may support one or multiple (e.g., two, three, four,and the like) cells.

The base station 103 may include an evolved Node B (eNB), for example.Accordingly, a base station 103 may also be referred to as a basetransceiver station, an access point (AP), an eNB, or a wireless networkhub. Although FIG. 1 only shows one base station 103, it will berecognized that there could be many base stations 103 within thecommunications environment 100, as well as be an assortment of differenttypes such as macro and/or small (e.g., pico, femto, etc.) basestations. The base stations 103 may also communicate with one anotherdirectly or indirectly, such as via a core network 111.

The communications environment 100 may support synchronous orasynchronous operation. For synchronous operation, the base stations 103may have similar frame timing, and transmissions from different basestations 103 may be approximately aligned in time. For asynchronousoperation, the base stations 103 may have different frame timing, andtransmissions from different base stations 103 may not be aligned intime.

In particular, two or more UEs 101, 102 may be used in conjunction totransmit signals across the same unlicensed network channel. Thecommunications environment 100 may support operation on multiplecarriers (e.g., waveform signals of different frequencies).Multi-carrier transmitters can transmit modulated signals simultaneouslyon the multiple carriers. For example, each modulated signal may be amulti-carrier channel modulated according to the various radiotechnologies described above. Each modulated signal may be sent on adifferent carrier and may carry control information (e.g., pilotsignals, control channels, etc.), overhead information, data, etc. Thecommunications environment 100 may be a multi-carrier LTE networkcapable of efficiently allocating network resources. The communicationsenvironment 100 is one example of a network to which various aspects ofthe disclosure apply.

Referring to FIG. 2, the system 108 comprises one or more UEs 101, 102.In one embodiment such as that shown in FIG. 2, two or more UEs 101 arelocated within a licensed network area 104 and are further locatedwithin an 802.11 network area 105 that is illustrated with a dashedline. In some cases, UEs 101, 102 are in wireless communication with abase station 103. One or more of these devices may be compatible with802.11 networks.

In another embodiment (not shown in FIG. 2), a single UE 101 is incommunication with the base station 103. The UE 101 may be capable oftransmitting and receiving wireless signals from two or more networkstandards including 802.11 signals and 5G signals.

In another embodiment (not shown in FIG. 2), one or more UEs may not bewithin range of one of the two network areas 104, 105.

FIG. 3 shows an exemplary wireless communication device 110. Thewireless communication device 110 comprises components that may beinterconnected internally including a processor 114, memory 116,coexistence module 120, transceiver 122, and antenna module 128.

In one aspect, the wireless communication device 110 can serve as anevolved Node B (eNB), a generic access point (AP), or a stationary basestation (e.g., base station 103 of FIGS. 1 and 2) that is connected to awireless network via an antenna 130. In another aspect, the wirelesscommunication device 110 can serve as a UE (e.g., UEs 101 and 102 ofFIGS. 1 and 2) and be utilized by an end user to communicate with awireless network.

The wireless communication device 110 is capable of managing coexistencebetween signals of two or more wireless standards on an unlicensed band.The processor 114 of the device 110 processes signals from the device110 and may decode transmissions from a connected wireless network. Amemory 116 may contain volatile or non-volatile storage devices as wellas instructions 118 for decoding, transmitting, and managing wirelesssignals. Although memory 116 is shown to be separate from processor 114,persons skilled in the art will appreciate that memory 116 can entirelybe on-board processor 114 or at least one portion of memory 116 can beon-board processor 114.

The coexistence module 120 of the device 110, in conjunction with theantenna module 128 may scan unlicensed bands to determine signal trafficloads on channels of the network. In one embodiment, the coexistencemodule 120 and the antenna module 128 may be configured to passivelyscan one or more unlicensed band channels. In another embodiment, thecoexistence module 120 and the antenna module 128 may be configured toactively scan one or more unlicensed band channels. In yet anotherembodiment, the coexistence module 120 and the antenna module 128 mayperform both passive and active scans of one or more unlicensed bandchannels. The coexistence module 120 may allow the device 110 toimplement dynamic duty cycles as discussed below. The coexistence module120 may be implemented in hardware, software, firmware, or anycombination of the above.

In some embodiments, the device 110 comprises a transceiver 122 that iscompatible with 802.11 signals. The transceiver 122 is equipped with amodem subsystem 124 and an RF unit 126 that communicates with theantenna module 128. Finally, antenna 130 transmits and receivestransmissions through the antenna module 128.

In one embodiment, one or more wireless communication devices 110 maymonitor unlicensed band channels to determine signal traffic loads andminimize interference with ongoing 802.11 transmissions. The flowchartof FIG. 4 shows a general method 400 for channel selection and trafficmonitoring. Method 400 may be performed by a wireless communicationdevice 110 (FIG. 3) or a base station 103. As discussed above, wirelesscommunication device 110 may be a base station (e.g., base station 103of FIGS. 1 and 2) or a UE (e.g., UEs 101 and 102 of FIGS. 1 and 2).

At block 402, one or more wireless communication devices 110 may selecta channel of an unlicensed 802.11 band for data transmission. Forexample, processor 114 of wireless communication device 110 (FIG. 3) mayselect a channel of an unlicensed 802.11 band for band transmission.

At block 404, the one or more devices 110 may monitor 802.11 signaltraffic on the selected channel during designated time slots. In oneembodiment, the block 404 is performed by a single device 110 thatcontinuously monitors the selected channel, as in the case of LTE-UAccess Points (as discussed below in conjunction with FIGS. 5 and 6).For instance, co-existence module 120 of FIG. 3 may monitor 802.11signal traffic on the selected channel during the designated time slots.The co-existence module 120 may use passive or active monitoring. Inthis embodiment, the device 110 that monitors the channel maycommunicate the result of its scans to other devices 110, eitherdirectly or through a network hub such as a base station 103.

In another embodiment, more than one wireless communication device 110may monitor the selected channel. In this case, each device 110 maycomplete a passive or active scan of the unlicensed network. Forinstance, a co-existence module 120 of each device 110 may monitor802.11 signal traffic on the selected channel during the designated timeslots. When multiple devices are used, each device 110 may scan multiplechannels of the unlicensed band. In some embodiments, each device 110may communicate the result of its respective scans to the other devices110, either directly or through a network hub such as a base station103. This approach may allow the devices 110 to compile more accuratesignal traffic load results than would be possible for each of thedevices 110 alone. These embodiments may lessen the power requirementsof the device 110 and may also decrease the duty cycle length of thescan.

At block 406, the one or more devices 110 may determine whether 802.11signal traffic is present on the selected channel during the designatedtime slots. For example, processor 114 may determine based on theinformation provided by the coexistence module 120 whether any 802.11signals have been received. In one embodiment, the traffic load ismeasured by totaling the total amount of monitored 802.11 signalsmeasured by the one or more devices 110. In other embodiments, mean ormedian measurements of signal traffic measured by two or more devices110 are used to establish the total traffic load.

In some cases, any signal traffic on the unlicensed band will requirethe device 110 to take additional steps before transmitting a wirelesssignal on the unlicensed network. Accordingly, in one aspect, if 802.11signal traffic has been determined to be present on the selected channelduring the designated time slot, method 400 may proceed to optionalblock 408. For example, processor 114 may implement a dynamic duty cycleif it is determined that 802.11 signal traffic is present on theunlicensed band channel. Processor 114 may implement the dynamic dutycycle by adjusting the spacing of designated time slots to take intoaccount 802.11 signal traffic. Block 408 is further discussed inconjunction with FIGS. 7 and 8. After the dynamic duty cycle isimplemented, the device 110 may continue to monitor 802.11 traffic on aselected channel at block 404.

On the other hand, if 802.11 signal traffic has not been determined tobe present on the selected channel during the designated time slot,method 400 may proceed to block 410. At block 410, the one or moredevices may make data transmission during the designated time slots. Forexample, the processor 114 may implement instructions 118 from memory116 that cause the transceiver 122 in conjunction with the antennamodule 128 to transmit data via the antenna 130. After making the datatransmissions, the one or more device may then continue to monitor802.11 traffic at block 404.

FIG. 5 shows a method 500 of passively monitoring 802.11 signal trafficon an unlicensed band channel. Method 500 may be performed by a wirelesscommunication device 110 (FIG. 3). As discussed above, wirelesscommunication device 110 may be a base station (e.g., base station 103of FIGS. 1 and 2) or a UE (e.g., UEs 101 and 102 of FIGS. 1 and 2).

At block 502, device 110 may select a channel from the unlicensed bandchannels. For example, processor 114 of wireless communication device110 (FIG. 3) may select a channel of an unlicensed 802.11 band for bandtransmission. This channel may be selected on the basis of previoussignal traffic measurements or may simply be selected as a matter ofcourse as device 110 scans an unlicensed band.

At block 504, the device 110 may passively listen for 802.11 signaltraffic on the selected channel. For instance, co-existence module 120may monitor 802.11 signal traffic on the selected channel.

At block 506, the device 110 may determine if it has found a cleanchannel. As used herein, “a clean channel” can refer to a channel thatis completely clear of 802.11 signal traffic.

For example, processor 114 may determine based on the informationprovided by the coexistence module 120 whether any 802.11 signals havebeen received. If no 802.11 signals have been received, then the channelis clean.

In the case that the channel is completely clear of 802.11 signaltraffic, the device 110 may transmit a signal on the channel at block508. For example, the processor 114 may implement instructions 118 frommemory 116 that cause the transceiver 122 in conjunction with theantenna module 128 to transmit data via the antenna 130.

If the device 110 determines that the channel is not completely clear oftraffic, the device may continue to monitor channels on the unlicensedband to choose a channel with the least amount of signal traffic atblock 510. For example, as in block 506, processor 114 may determinebased on the information provided by the coexistence module 120 how many802.11 signals have been received. As discussed earlier, thismeasurement of signal traffic may take into account traffic measurementsby other devices 110. For example, processor 114 may determine a trafficload measurement by total, mean, or median amounts of signal trafficmeasured by the one or more devices.

In one embodiment, the device(s) 110 may implement simple channelselection and the processor 114 may choose the channel with the lowestnumber of signal responses (including no detected signal traffic) thatare detected by device(s) 110. In another embodiment, the device(s) 110may implement advanced signal selection, for example by the processor114 implementing advanced signal selection instructions 118 from memory116, and the channel with the lowest amount of signal traffic may bechosen. This embodiment may involve monitoring secondary channels on theunlicensed network. Upon selecting a channel with the least amount ofsignal traffic, the device 110 may transmit the signal on the channel atblock 508, as described above.

FIG. 6 shows a method 600 of actively monitoring 802.11 signal trafficon an unlicensed band channel. Method 600 may be performed by a wirelesscommunication device 110 (FIG. 3). As discussed above, wirelesscommunication device 110 may be a base station (e.g., base station 103of FIGS. 1 and 2) or a UE (e.g., UEs 101 and 102 of FIGS. 1 and 2).

At block 602, device 110 may select a channel from the unlicensed bandchannels. For example, processor 114 of wireless communication device110 (FIG. 3) may select a channel of an unlicensed 802.11 band for bandtransmission. As in block 502 of FIG. 5, this channel may be selected onthe basis of previous signal traffic measurements or may simply beselected as a matter of course as a device 110 scans an unlicensed band.

At block 604, the device 110 may transmit a probe signal on the selectedunlicensed band channel. For example, processor 114 may causecoexistence module 120 in conjunction with antenna module 128 totransmit the probe signal. In some instances, the device 110 maytransmit a probe signal on multiple unlicensed band channels.

At block 606, the device 110 may actively listen for signal traffic.That is, the device 110 may listen for probe responses from one or moreaccess points or other wireless communication devices operating on theunlicensed band(s). For instance, co-existence module 120 may monitorthe selected channel for responses to the probe signal.

At block 608, the device 110 may determine whether a clean channel isfound (e.g., the channel is completely clear of 802.11 signal traffic).For example, the processor 114 may determine whether any probe responseshave been received by the device 110. If the device 110 determines thata clean channel has been found, at block 610, the device 110 maytransmit a signal on the channel.

If the device 110 instead determines that a clean channel has not beenfound (e.g., the channel is not completely clear of 802.11 traffic), thedevice may continue to monitor channels on the unlicensed band to choosea channel with the least amount of signal traffic at block 612. Forexample, as in block 608, processor 114 may determine whether how manyprobe responses have been received by the device 110. As discussedearlier, this measurement of signal traffic may take into accounttraffic measurements by other devices 110 and may determine a trafficmeasurement by total, mean, or median amounts of signal traffic measuredby the one or more devices.

After the device 110 has chosen a channel with the least amount ofsignal traffic, it may transmit a signal at block 610, as describedabove.

The flow diagram of FIG. 7 shows an exemplary method 700 of implementinga dynamically varying duty cycle. Method 700 may be performed by awireless communication device 110 (FIG. 3). As discussed above, wirelesscommunication device 110 may be a base station (e.g., base station 103of FIGS. 1 and 2) or a UE (e.g., UEs 101 and 102 of FIGS. 1 and 2).

At block 702, one or more wireless communication devices 110 may selecta channel on an unlicensed band network as previously discussed. Forexample, processor 114 of wireless communication device 110 (FIG. 3) mayselect a channel of an unlicensed 802.11 band for band transmission.This channel may be selected on the basis of previous signal trafficmeasurements or may simply be selected as a matter of course as device110 scans an unlicensed band.

At block 704, the device 110 may divide time on the channel intomultiple time slots. For example, processor 114 may logically separatethe channel into increments of a specified duration. In one embodiment,the duration for each time slot may be 10 ms or more. In anotherembodiment, the duration of each time slot may be less than 10 ms.

At block 706, the device 110 may select a subset of time slots from themultiple time slots. In one embodiment, the processor 114 may select asubset that may contain a number of consecutive time slots. In anotherembodiment, the selected subset of time slots may be separated by arandom number of unselected time slots. In one aspect, the number ofunselected time slots placed between selected time slots may depend on802.11 signal traffic loads on the channel.

At block 708, device(s) 110 may determine if there is traffic (e.g.,802.11 signal traffic) in the selected subset of time slots by passivelyor actively monitoring 802.11 signal traffic on the selected channelduring the selected subset of time slots. In an aspect, the passive andactive monitoring may proceed in a similar way as described in block 504of method 500 (FIG. 5) and block 606 of method 600 (FIG. 6),respectively.

If it is determined that there is no traffic in the selected subset oftime slots as described, for example, in block 506 of method 500 andblock 608 of method 600, the device(s) 110 may transmit a signal duringthe selected subset of time slots at block 710, as described above.

If it is determined that there is traffic in the selected subset of timeslots, the device(s) 110 may adjust the spacing of the selected subsetof time slots at block 712. In one embodiment, as larger signal trafficvolumes are measured by the device 110 on the channel, processor 114 mayupdate its selection of time slots by selecting a subset of time slotsthat are farther apart from each other. This may help to minimize therisk of collisions between 802.11 signals and other wireless signalstransmitted by the device 110. Thus, one aspect of a “dynamic dutycycle” or “dynamically varying duty cycle” may include selecting asubset of time slots and adjusting the spacing between the selectedsubset of time slots based on signal traffic.

Along with selecting time slots based on signal traffic, another aspectof the dynamic duty cycle of the present disclosure may also includesubdividing time slots. FIG. 8 shows a flow diagram of an exemplarymethod 800 of subdividing time slots for signal traffic monitoring.Method 800 may be performed by a wireless communication device 110 (FIG.3). As discussed above, wireless communication device 110 may be a basestation (e.g., base station 103 of FIGS. 1 and 2) or a UE (e.g., UEs 101and 102 of FIGS. 1 and 2).

At block 802, device 110 may select a channel on an unlicensed band aspreviously discussed. For example, processor 114 of wirelesscommunication device 110 (FIG. 3) may select a channel of an unlicensed802.11 band for band transmission. This channel may be selected on thebasis of previous signal traffic measurements or may simply be selectedas a matter of course as device 110 scans an unlicensed band.

At block 804, device 110 may divide time on the channel into a pluralityof time slots, as described above at block 704 of method 700 (FIG. 7).For example, processor 114 may logically separate the channel intoincrements of a specified duration. In one embodiment, the duration foreach time slot may be 10 ms or more. In another embodiment, the durationof each time slot may be less than 10 ms.

At block 806, device 110 may select a subset of time slots for signaltraffic monitoring at, as discussed in conjunction with block 706 ofmethod 700 (FIG. 7). In one embodiment, the processor 114 may select asubset that may contain a number of consecutive time slots. In anotherembodiment, the selected subset of time slots may be separated by arandom number of unselected time slots. In one aspect, the number ofunselected time slots placed between selected time slots may depend on802.11 signal traffic loads on the channel.

At block 808, device 110 may divide each selected time slot into aplurality of sub-slots (e.g., k, k+1 . . . n). In one embodiment,processor 114 may divide subsets into sub-slots may have a duration of 5ms or less. In another embodiment, processor 114 may divide subsets intosub-slots that have a duration of 20 ms or less.

At block 810, if an initial sub-slot (sub-slot k) is found to be clearof 802.11 signal traffic, the device 110 may transmit a signal duringthat sub-slot at block 432, as described above. For example, device(s)110 may determine if there is traffic (e.g., 802.11 signal traffic) inthe selected subset of time slots by passively or actively monitoring802.11 signal traffic on the selected channel during the selected subsetof time slots. In an aspect, the passive and active monitoring mayproceed in a similar way as described in block 504 of method 500 (FIG.5) and block 606 of method 600 (FIG. 6), respectively.

Alternatively at block 810, if an initial sub-slot (sub-slot k) is foundto be occupied with an 802.11 transmission, then the device 110 maymonitor a subsequent sub-slot (sub-slot k+1) at block 814. In anembodiment, monitoring sub-slot k+1 occurs in a manner consistent withmonitoring sub-slot k in block 808.

As before, the device may transmit a signal during sub-slot k+1 if nosignal traffic is found (block 432). If signal traffic is found, atblock 816, the device(s) may continue to monitor signal traffic in theremaining sub-slots up to sub-slot n with the same monitoring methoddescribed at block 808.

After the final sub-slot (sub-slot n) of the time slot is monitored atblock 816, or a signal is transmitted by the device(s) at block 432, themethod 800 may return to block 808, and the processor 114 of device(s)110 may select another time slot and subdivide it. Accordingly, method800 may increase the likelihood of access for wireless networktransmissions on unlicensed bands by allowing transmissions in timeslots where 802.11 traffic will be present for only part of the timeslot. For example, if there is 802.11 traffic only occupying onlyinitial sub-slot k of a time slot, subdivision into sub-slots allows thedevice 110 to transmit at sub-slot k+1 rather than having to wait untilthe next time slot in the subset.

In one embodiment, the processor 114 excludes one or more sub-slots ofthe from monitoring as part of the dynamic duty cycle. In this case, thedynamic duty cycle includes sub-slots (e.g., k, k+1 . . . n-x . . . n)only until the n-x sub-slot. Monitoring only this set of sub-slots maypreserve one or more sub-slots after sub-slot n-x that would not providesufficient time to send a transmission, or may eliminate monitoringsub-slots that are not required for transmission. In another embodiment,the number of sub-slots monitored included in the dynamic duty cycle isvaried based on the amount of data that the system is required to send.In this case, y is the number of sub-slots needed to transmit a datapacket and the device 110 only monitors subslots (k, k+1 . . . n-x . . .n) until the sub-slot n-x is monitored, where x is larger than y.

FIGS. 9-11 show further examples of time slot selection and subdivisionin accordance with the dynamic duty cycle of the present disclosure, asdescribed above with reference to FIGS. 7-8. FIG. 9 shows an exemplaryset of transmissions 900 during a time period on an unlicensed bandchannel. 802.11 transmissions 902, 906 are represented by unshaded boxesand are transmitted at several times during the time period. Otherwireless network signals 904, 908, which may be 5G transmissions, arerepresented by shaded boxes and are also present on the unlicensed bandchannel. The transmissions do not overlap to avoid signal collisions.Collision avoidance is achieved using the channel selection and signalmonitoring of FIGS. 4-6 and dynamic duty cycle is implemented accordingto FIGS. 7-8. In some embodiments, the transmissions 902, 904, 906, 908are spaced to allow adequate room for any necessary signal preambles orguard intervals to ensure that transmissions do not collide.

FIG. 10 shows an exemplary set of time slot divisions 1000 during a timeperiod on an unlicensed band channel, in conjunction with the discussionof time slots in FIG. 7. In this example, the time period is subdividedinto a plurality of time slots 1010, 1012, 1014, 1016. A device 110(FIG. 3) may select a subset of these time slots, as described at block706 of method 700, and determine whether there is an 802.11 transmissionassociated with each time slot of the selected subset of time slots, asdescribed at block 708 of method 700. In an embodiment, the device 110monitors the channel for at least the length of a Short Interframe Space(SIFS) or PCF Interframe Space (PIFS) to determine whether an 802.11transmission is present. This ensures that the device 110 does notmonitor during an interframe space of an active 802.11 transmission,which would result in a false positive determination that the channel isclear.

In this example, shaded time slots 1010, 1012, 1014 have been selectedby the device, and these eligible time slots will be passively oractively monitored for signal traffic, as described in methods 500(FIGS. 5) and 600 (FIG. 6), respectively. Unshaded time slots 1016 arenot selected and will not be monitored for signal traffic. In theexample of FIG. 10, a random number of unselected time slots are placedin between selected time slots. As discussed in conjunction with FIG. 7,the number of unselected time slots placed between selected time slotsmay increase in proportion to 802.11 signal traffic on the channel. Inanother embodiment not shown in FIG. 10, sequential time slots areselected by the device 110 for traffic monitoring.

FIG.11 shows a plurality of time slots 1100 on an unlicensed bandchannel in conjunction with the discussion of sub-slots in FIG. 8.Shaded time slots 1010, 1012, 1014 have been selected by a wirelesscommunication device 110 for signal traffic monitoring. These time slotswere consequently subdivided into a number of sub-slots as described atblock 808 of method 800. Time slot 1010 was found to have no 802.11signal traffic at the time of monitoring, so the device 110 may transmita transmission during the entire time slot 1010, as described above.Time slots 1012, 1014 were found to have 802.11 signal traffic at thetime of monitoring (i.e., at initial sub-slot 1102). After the device110 has determined the traffic loads for each of the sub-slots, thedevice 110 may transmit on the channel during sub-slots 1104 that arefound to be clear of 802.11 signal traffic. In some embodiments, thedevice 110 may select to transmit during sub-slots 1102, 1104 that haveless signal traffic than other sub-slots 1102, 1104. In the example ofFIG. 11, unselected time slots are not subdivided. In other embodiments,a subset of unselected time slots may also be subdivided.

FIGS. 12-17 describe various ways in which device 110 of FIG. 3 maydetect the presence or absence of 802.11 signals in a channel inconjunction with FIGS. 4-8 above.

FIG. 12 shows an exemplary 802.11 transmission 1200 with preambles 1202,1204, 1206. In one embodiment, the coexistence module 120 in conjunctionwith the antenna module 128 receives the preambles 1202, 1204, 1206 viaantenna 130 from the wireless network. In one embodiment, the processor114 decodes preambles and headers that are prepended to an 802.11wireless network Protocol Data Unit (PPDU) 1208 in a complete 802.11transmission 1200 in order to detect an 802.11 transmission. Theprocessor 114 of device 110 (FIG. 3) may be configured to decode theShort Training Field (STF) 1202 to determine if an 802.11 transmissionis ongoing on an unlicensed band. The format of the STF 1202 isdistinct, and indicates to any device capable of decoding it that an802.11 transmission is commencing. The processor 114 may also decode theLong Training Field (LTF) 1204 to estimate the channel on which thetransmission 1200 is ongoing. Finally, the processor 114 may decode theLegacy-Compatible Signal Field (LSIG) which includes information in bitform about the rate 1210, length 1212, and toil 1214 of the entiretransmission 1200. By knowing the channel and duration of the 802.11transmission, a device 110 can schedule wireless network transmissionsthat do not interfere with the 802.11 transmission. Although this methodmay allow the device 110 to effectively avoid collision with 802.11traffic, the device may need to detect transmission 1200 from thebeginning to decode the preambles 1202, 1204, 1206.

An alternative method, which may be used in conjunction with decodingpreambles, is to detect guard intervals that may be present on 802.11transmissions. This may allow a device 110 to detect an ongoing 802.11transmission in the event that the device 110 is not listening duringthe preambles 1202, 1204, 1206. FIG. 13 shows an exemplary 802.11transmission 1300 with an 802.11 PPDU 1304 surrounded by OrthogonalFrequency-Division Multiplexing (OFDM) symbols 1302. In one embodiment,the coexistence module 120 in conjunction with the antenna module 128receives the OFDM symbols 1302 via antenna 130 from the wirelessnetwork. In one embodiment, processor 114 of a device 110 (FIG. 3) maybe configured to detect if OFDM symbols 1302 are present on anunlicensed channel by detecting the time between cyclical prefixes.802.11 transmissions are known to use OFDM symbols that are 4 μs inlength with a 0.8 μs cyclical prefix (i.e., the first and last 0.8 μs ofany OFDM symbol are identical). In some embodiments, the processor 114may be configured to compute a moving average over 0.4 μs to detect 0.8μs cyclical prefixes that occur 2.4 μs apart, indicating that 4 μs OFDMsymbols are present on the channel, which further indicates to a highdegree of certainty that an 802.11 transmission is ongoing.

The device(s) 110 can also be configured to provide signaling to 802.11devices indicating the presence of and/or scheduling of 5G unlicensedtransmissions in order to avoid collision with the 802.11 devicetransmissions. This can be done by sending signals that the 802.11protocol recognizes for scheduling. For example, the device(s) 110 cantransmit 802.11 Request to Send (RTS) and/or Clear to Send (CTS) signalsthat can be received and interpreted by 802.11 compatible devices toeffectively reserve time slots for the wireless transmissions as shownin FIGS. 14-16. The RTS and CTS indicate to 802.11 compatible devices todefer transmissions by a time length indicated in the RTS and CTS.

In FIG. 14, a diagram 1400 of transmission (Tx) and receiver (Rx)functions of a device 110 (FIG. 3) are shown. The device 110 transmitsan RTS signal 1402 prior to the wireless network PPDU 1406 during atransmission period of the device. As noted above, this indicates to alldevices in range that they should defer transmissions for an indicatedlength of time. The device 110 may be configured to leave a transmissiongap for a CTS signal 1404 to be received by the receiver of the device110. All devices that receive the RTS signal 1402 should send a CTSsignal 1404 in response, thereby ensuring that anything in range of thereceiving device is also deferring transmissions to keep the channelclear for receipt.

In FIG. 15, diagram 1500 of transmission (Tx) and receiver (Rx)functions of a device 110 (FIG. 3) are shown. In this embodiment, thedevice 110 sends only a CTS signal 1404, which may be self-addressed.The CTS and RTS serve the same function of causing all devices in rangeto defer transmission to keep the channel clear, however, by not sendingan RTS the device 110 need not wait for all receiving devices to send aCTS in response. This lowers overhead. Because 5G transmissions do notrequire a SIFS (as may be required by 802.11 transmissions), a wirelessnetwork PPDU 1406 may be sent by device 110 directly after finishingtransmission of the CTS signal 1404. In one aspect (shown in FIGS.14-16), the CTS signal 1404 may be configured to include information onthe length of the PPDU 1406 to alert 802.11 compatible devices accessingthe unlicensed network to defer transmissions for the time correspondingto the length of the PPDU 1406.

In FIG. 16, diagram 1600 of transmission (Tx) and receiver (Rx)functions of a device 110 (FIG. 3) are shown, describing an embodimentsimilar to that of diagram 1500. In this embodiment, unlike that ofdiagram 1500, receiving 802.11 compatible devices may transmit a CTS1602 at the same time that the device 110 (FIG. 3) may transmit a CTSsignal 1404. This has the advantage of ensuring that nodes that may bein range of receiving devices but not in range of the device 110 arenotified by the CTS signal to defer transmissions and keep the channelclear. This approach may therefore better protect the transmissions ofdevice 110 from hidden 802.11 nodes. In some embodiments, this ispossible because cellular wireless protocols such as LTE, 5G, etc. allowthe assumption that UEs 101, 102 and base stations 103 have synchronizedtiming, and a simultaneous transmission of a CTS signal may be arranged.

In some embodiments, the collision avoidance signals described in FIGS.14-16 may be decoded by both 802.11 compatible devices and devicescompatible with other radio access technologies (RATs) such as LTE, 5G,etc. This allows a single collision avoidance signal to serve for both802.11 and other RATs without using further network resources.

The flowchart of FIG. 17 shows an exemplary method 1700 of implementingcollision avoidance signaling in accordance with FIGS. 14-16. Beginningat block 1701, the processor 114 of device 110 (FIG. 3) may decide tosend collision avoidance signals to 802.11 compatible devices. Moving todecision block 1702, the processor 114 may choose between sending an RTSsignal in accordance with the embodiment of FIG. 14 or sending a CTSsignal in accordance with the embodiments of FIGS. 15-16.

If the processor 114 chooses to send an RTS signal, the method 1700progresses to block 1704, and the processor 114 causes the transceiver122 in conjunction with the antenna module 128 to transmit an RTS signal1402, as described above with reference to FIG. 14. Moving to block1706, the device 110 receives CTS signals 1404 from devices thatreceived the RTS signal 1402, as described above with reference to FIG.14. Moving to block 1708, the device may transmit a wireless networkPPDU 1406, as described above with reference to FIG. 14.

Returning to decision block 1702, if the processor 114 chooses to send aCTS signal, for example to reduce overhead, the method 1700 proceeds toblock 1710, and the processor 114 causes the transceiver 122 inconjunction with the antenna module 128 to transmit an CTS signal 1404,as described above with reference to FIG. 15. Moving to block 1708, thedevice may immediately transmit a wireless network PPDU 1406, asdescribed above with reference to FIG. 15. In some embodiments, asdescribed by FIG. 16, device 110 may send a CTS signal 1404 while 802.11compatible devices in range to receive the CTS signal 1404simultaneously send their own CTS signal 1602. In this case, at block1712, the device 110 receives the CTS signals 1602 from 802.11compatible devices at the same time as it sends the CTS signal 1404 inblock 1710.

As an alternative to prepending RTS and CTS signals to a wirelesstransmission, a device 110 may also be able to alert 802.11 compatibledevices on an unlicensed band to other types of the impendingnon-802.011 transmissions (e.g., 5G transmissions) of device 110 byinserting 802.11 preambles into wireless network transmissions. Forexample, as shown in FIG. 18, 802.11 preambles 1802 may be inserted intowireless transmission 1800. In this case, one or more 802.11 preambles1802, which may comprise STF 1202, LTF 1204, and LSIG signals 1206, areinserted before each wireless network PPDU 1406. These 802.11 preambles1802 may alert 802.11 compatible devices on an unlicensed band toimpending wireless network transmissions.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the above description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a DSP, an ASIC, an FPGA or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration).

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope of the disclosure and appended claims. For example, due to thenature of software, functions described above can be implemented usingsoftware executed by a processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations. Also, as used herein, including in the claims, “or ” as usedin a list of items (for example, a list of items prefaced by a phrasesuch as “at least one of” or “one or more of”) indicates an inclusivelist such that, for example, a list of [at least one of A, B, or C]means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Asthose of some skill in this art will by now appreciate and depending onthe particular application at hand, many modifications, substitutionsand variations can be made in and to the materials, apparatus,configurations and methods of use of the devices of the presentdisclosure without departing from the spirit and scope thereof. In lightof this, the scope of the present disclosure should not be limited tothat of the particular embodiments illustrated and described herein, asthey are merely by way of some examples thereof, but rather, should befully commensurate with that of the claims appended hereafter and theirfunctional equivalents.

1. A method for managing wireless communications, the method comprising:determining, by a first wireless communication device configured tocommunicate using a first radio access technology and a second radioaccess technology, to send one or more collision avoidance signals bythe second radio access technology; transmitting, using the firstwireless communication device, the one or more collision avoidancesignals to one or more receiving wireless communication devices, the oneor more collision avoidance signals formatted to allow the one or morereceiving wireless communication devices to receive the one or morecollision avoidance signals using the first radio access technology, theone or more collision avoidance signals also including information toallow the one or more receiving wireless communication devices to avoidtransmission collisions with the first wireless communication deviceduring a transmission time slot; and communicating, using the firstwireless communication device, data with a second wireless communicationdevice using the second radio access technology during the transmissiontime slot, wherein the second radio access technology is different thanthe first radio access technology.
 2. The method of claim 1, wherein thetransmitting the one or more collision avoidance signals includestransmitting a request to send (RTS) signal to the second wirelesscommunication device, the method further comprising receiving, using thefirst wireless communication device, one or more clear to send (CTS)signals.
 3. The method of claim 1, wherein the transmitting the one ormore collision avoidance signals includes transmitting a clear to send(CTS) signal to the one or more receiving wireless communicationdevices.
 4. The method of claim 1, further comprising receiving one ormore first clear to send (CTS) signals using the first wirelesscommunication device, wherein the transmitting the one or more collisionavoidance signals includes transmitting a second CTS signal to the oneor more receiving wireless communication devices simultaneously with thereceiving one or more first CTS signals.
 5. The method of claim 1,wherein the transmitting the one or more collision avoidance signalsincludes transmitting an unlicensed preamble to the second wirelesscommunication device.
 6. A first wireless communication device thatcommunicates using a first radio access technology and a second radioaccess technology, comprising: a processor and a co-existence modulethat monitor a channel of an unlicensed band during a subset of timeslots of the channel and configured to determine to send one or morecollection avoidance signals by the second radio access technology; anda transmitter configured to: transmit the one or more collisionavoidance signals to one or more receiving wireless communicationdevices, the one or more collision avoidance signals formatted to allowthe one or more receiving wireless communication devices to receive theone or more collision avoidance signals using the first radio accesstechnology, the one or more collision avoidance signals also includinginformation to allow the one or more receiving wireless communicationdevices to avoid transmission collisions with the first wirelesscommunication device during a transmission time slot; and communicatedata with a second wireless communication device using the second radioaccess technology during the transmission time slot, wherein the secondradio access technology is different than the first radio accesstechnology.
 7. The device of claim 6, wherein the one or more collisionavoidance signals include a request to send (RTS) signal transmitted tothe second wireless communication device and one or more clear to send(CTS) signals transmitted to the first wireless communication device. 8.The device of claim 6, wherein the one or more collision avoidancesignals includes a clear to send (CTS) signal transmitted to the one ormore receiving wireless communication devices.
 9. The device of claim 6,further comprising a receiver configured to receive one or more firstclear to send (CTS) signals, wherein the one or more collision avoidancesignals includes a second CTS signal transmitted to the one or morereceiving wireless communication devices simultaneously with thereceiver receiving the one or more first CTS signals.
 10. The device ofclaim 6, wherein the one or more collision avoidance signals includes anunlicensed preamble transmitted to the second wireless communicationdevice.
 11. A first wireless communication device that communicatesusing a first radio access technology and a second radio accesstechnology, comprising: means for determining to send one or morecollision avoidance signals by the second radio access technology; meansfor transmitting the one or more collision avoidance signals to one ormore receiving wireless communication devices, the one or more collisionavoidance signals formatted to allow the one or more receiving wirelesscommunication devices to receive the one or more collision avoidancesignals using the first radio access technology, the one or morecollision avoidance signals also including information to allow the oneor more receiving wireless communication devices to avoid transmissioncollisions with the first wireless communication device during atransmission time slot; and means for communicating data with a secondwireless communication device using the second radio access technologyduring the transmission time slot, wherein the second radio accesstechnology is different than the first radio access technology.
 12. Thedevice of claim 11, wherein the means for transmitting the one or morecollision avoidance signals includes means for transmitting a request tosend (RTS) signal to the second wireless communication device andtransmitting one or more clear to send (CTS) signal to the firstwireless communication device.
 13. The device of claim 11, wherein themeans for transmitting the one or more collision avoidance signalsincludes means for transmitting a clear to send (CTS) signal to the oneor more wireless receiving communication devices.
 14. The device ofclaim 11, further comprising: means for receiving one or more firstclear to send (CTS) signals; and means for transmitting a second CTSsignal to the one or more receiving wireless communication devicessimultaneously with the receiving the one or more CTS signals.
 15. Thedevice of claim 11, wherein the means for transmitting the one or morecollision avoidance signals includes means for transmitting anunlicensed preamble to the second wireless communication device.
 16. Themethod of claim 1, wherein the first radio access technology is an802.11 radio access technology.
 17. The device of claim 6, wherein thefirst radio access technology is an 802.11 radio access technology. 18.The device of claim 11, wherein the first radio access technology is an802.11 radio access technology.